The membranes of Staphylococcus aureus and most Gram-positive bacteria consist of plasma membranes and lipoteichoic acid-containing mesosomes. The purpose of this study has been to determine the functional role of plasma membranes, mesosomes and lipoteichoic acid in the growth of the bacterial cell. Experiments have been designed to determine: (1) if mesosomes are derived from plasma membranes; (2) what degradative enzymes act on lipoteichoic acid; and (3) how the presence of alanine attached to LTA affects the dissociation of LTA aggregates.